Doctors in Israel conducted a double-blind placebo-controlled study to investigate the use of capsaicin in the treatment of pruritus ani.
The results of this study are published in the September issue of Gut.
The research team firstly established which of two doses of topical capsaicin was better tolerated and more effective in a pilot study of 5 patients.
After this first phase the research team moved on to study the efficacy of capsaicin in a double-blind placebo-controlled study.
44 patients were randomized into 2 equal sized groups to receive locally, either active capsaicin (0.006%) or placebo (menthol 1%) ointment over a four week period.
After 4 weeks of treatment and a 1-week washout period, the placebo group began to receive capsaicin while the treated group received placebo (menthol 1%) for another 4 weeks.
31 of the 44 patients experienced relief during capsaicin treatment periods and did not respond to menthol.
During a mean 10.9 months of follow up, 29 patients who responded well to capsaicin treatment required an average of 1 application per day of capsaicin ointment to remain symptom free.
The authors of the study conclude. "Capsaicin is a new, safe, and highly effective treatment for severe intractable idiopathic pruritus ani."
| 31 of 44 patients experienced relief during capsaicin treatment |
An editorial in the same edition of Gut comments. "While both capsaicin and menthol application produce a transient perianal burning sensation, only capsaicin relieves itching."
"The recent discovery of a range of receptors which respond to capsaicin, menthol, and temperature, and their expression in subsets of sensory nerve fibres, provides an exciting prospect towards advancing our understanding and treatment of sensory dysfunction."